Field of the Invention
The present invention relates to a lens barrel in a lens apparatus, or more specifically, to a lens barrel including a lens barrel submodule to be moved in a direction of an optical axis by a cam mechanism, and to a lens apparatus and an image pickup apparatus including the lens barrel.
Description of the Related Art
In the field of a mechanism configured to move optical systems in directions of an optical axis by use of cams and cam followers, a structure configured to move each cam follower to one side of a groove by inserting an elastic member into a space between moving optical systems has been proposed as a structure to suppress backlash between the cams and the cam followers. Japanese Patent Application Laid-Open No. 2009-244585 describes a structure configured to suppress backlash by inserting a coil spring into each space between moving-part groups so as to bias the moving-part groups in mutually opposite directions.
However, according to the related art disclosed in Japanese Patent Application Laid-Open No. 2009-244585,an end face of such a coil spring is prone to come off the corresponding moving-part group, and the coil spring may intrude into an optical path as a consequence. In this regard, it is a general practice to bond the coil spring to the moving-part group so as to prevent the end face of the coil spring from coming off the moving-part group and intruding into the optical path. Here, each moving-part group includes a moving lens barrel supported by the cam through the cam follower, and a lens barrel unit attached to the moving lens barrel and configured to hold a lens. The coil spring is bonded to the moving lens barrel or the lens barrel unit (note that the moving lens barrel and the lens barrel unit are in together according to Japanese Patent. Application Laid-Open No. 2009-244585).
Nonetheless, when the coil spring is directly bonded to the moving lens barrel, the cam follower is fitted while biasing the moving lens barrel with the spring. Accordingly, this configuration has a problem of a difficulty in attaching the cam follower because the moving lens barrel is apt to be moved by a force of the spring. On the other hand, the configuration in which the coil spring is directly bonded to the lens barrel unit that holds the lens causes a problem of reduction in workability for attachment and detachment of the lens barrel unit during maintenance.